What is the deal with Soy and the Low FODMAP diet?
Soy beans are high FODMAP, right? And sometimes soy milk is Low FODMAP while soy flour can be a deal breaker. What is the deal with soy and FODMAPs- why is it sometimes ok for the Low FODMAP diet and sometimes not?
You can include soy in your Low FODMAP diet, with a little knowledge.
Soy beans are high in the FODMAP galacto-oligosaccharides or GOS for short. This is not surprising as GOS is generally found in legumes. The Monash Low FODMAP app does not state a Low FODMAP level of soy beans.
So soy beans and foods that contain soy bean as an ingredient are not considered low FODMAP- although there is an exception- see soy sauce below.
Edamame are soy beans which have been harvested early. Monash Low FODMAP app states that frozen edamame are Low FODMAP at one serve (1/2 cup) but turns into moderate FODMAPs at 1 ¼ cups.
In Australian, you can find soy milk products made from either soybean or soy protein extract. For soy products to be considered low in FODMAP it needs to come from the soy protein extract whereby the carbohydrate component (GOS) is removed in the processing.
Unfortunately, most products are from soybeans, which tend to be high in the FODMAP GOS. Soy milk products that are low FOMDAP currently available include So Good and Inner Health soy milk (Aldi).
Most soy yoghurt is made from soybeans so avoid, theoretically soy yoghurt can be made from soy protein but tend to also have a high FODMAP ingredient such as inulin adde. Rare as hen's teeth.
Coconut yoghurt is Low FODMAP for an alternative- but again check no sneaky FODMAPs such as fruit juice of inulin is added.
Tofu is also made from soybeans and it is the processing of this product which causes the FODMAPs to be separated, allowing it to be naturally low in FODMAPS. Firm tofu provides a very good source of protein. Both firm or plain tofu is lofo while silken tofu is high as it has not been pressed and drained like other tofu which means it retains the FODMAPs of the soybean.
Tempeh is also a great option (especially if you are vegan), it is high in protein, and although it is made whole soybeans, this product is fermented which reduces the FODMAP content.
Soy sauce is Low FODMAP for a normal serve, even if soy bean is listed on the ingredient list. The processing and fermentation reduces the FODMAP content and renders its low FODMAP.
High in FODMAPs and a real pain as often in foods that could have otherwise be low FODMAP. Ok as a minor ingredient, say up to 4g in a food serve, but avoid if a major ingredient.
Oils are made from fat and not carbohydrates so all oils, including soy oil, are low in FODMAPs.
The only exceptions are when high FODMAP ingredients may have been added such as garlic pieces, although garlic infused oil is quite acceptable.
Soy lecithin is added to foods to help with producing a better quality food product but has negligible carbohydrate so not a FODMAP.
Soy & FODMAP Content Summary
Summary of soy products and FODMAP content (taken from Monash Low FODMAP app and FODMAP Friendly app):
Soybeans (boiled): high in GOS at the ¼ cup
Edamame: lofo at the ½ cup, at 1 ¼ cup moderate in fructans
Soy milk: from soybeans (high in GOS)
Soy yoghurt: Low FODMAP if made from soy protein and not soy beans and make sure no other high FODMAP ingredients such as inulin
Soy cheese: 1 serve is lofo (2 slices=40g), increased amounts (2 cups=250g) is moderate in GOS and fructans
Tofu: plain not silken, and no upper limit given
Tempeh: lofo for a normal serve (100g) but turns to high FODMAP (fructans) if double this (well 220g to be precise!)
Soy sauce: lofo for a normal serve and no upper limit given
Soy flour: high FODMAP but okay up to 4g
Soy textured protein (TVP): high in GOS and fructans at 1 TBSP
False Chicken (soybeans): lofo at the ½ cup (50g), 1 cup is high in GOS, moderate in fructans
Soy has a number of possible health benefits. Knowing how to choose Low FODMAP forms of soy means you can continue to enjoy the health benefits ion soy while following a Low FODMAP diet.
Monash University FODMAP Diet app. Version 3.0.3. Accessed 18/6/19.
FODMAP Friendly app, Version 3.11. Accessed 18/6/19.
The Nutrition Source. (2019). Straight Talk About Soy. [online] Available at: https://www.hsph.harvard.edu/nutritionsource/soy/ [Accessed 18 Jun. 2019].